ABC News’ David Wright reports: At a joint rally in Cedar Rapids, Iowa Thursday, Republican John McCain slammed the Security and Exchange Commission (SEC) for being “asleep at the switch” saying that if he were president, he would fire Chris Cox, the chairman of the SEC since 2005 and a former Republican congressman.

McCain said the SEC has allowed trading practices such as short selling to stay in place that turned the “markets into a casino.”

“The regulators were asleep, my friends,” McCain said. “The chairman of the SEC serves at the appointment of the president. And in my view has betrayed the public trust. If I were president today, I would fire him.”

But while the president nominates and the Senate confirms the SEC chair, a commissioner of an independent regulatory commission cannot be removed by the president. From time to time, presidents have attempted to remove commissioners who have proven “uncooperative.”  However, the courts have general upheld the independence of commissioners. In 1935, President Franklin Delano Roosevelt fired a member of the Federal Trade Commission and the Supreme Court ruled the president acted unconstitutionally.  Asked how McCain would fire Cox if the president does not have the formal power to fire the chairman of the Securities and Exchange Commission, the McCain campaign pointed to former SEC Chairman Harvey Pitt who resigned in 2002 when it was made clear to him that he had lost the confidence of the Bush administration. “Not only is there historical precedent for SEC Chairs to be removed, the President of the United States always reserves the right to request the resignation of an appointee and maintain the customary expectation that it will be delivered,” said McCain spokesperson Tucker Bounds. The White House said this week it wants to stay out of politics, but a Bush administration spokesperson said today of SEC Chairman Cox, who was nominated by President George W. Bush: “the chairman has the president’s support.” Campaigning together in Iowa today McCain and Sarah Palin accused the Obama campaign of taking political advantage of the recent economic crisis.

“My opponent sees an economic crisis as a political opportunity instead of an opportunity to lead,” McCain said.

Said Palin of Obama: “He likes to point the finger of blame, but does he ever lift a finger to help?”

McCain accused Obama of taking more campaign contributions from Fannie Mae and Freddie Mac executives than anyone aside from the chair of the Congressional committee that regulates the lenders.

“While Sen. Obama was lining his pockets with campaign contributors, he didn’t lift a finger” said McCain, who took credit for warning Congress of the impending crisis two years ago.  McCain also noted that the former head of Obama’s vice presidential search committee Jim Johnson  was formerly a Fannie Mae executive.

The Obama campaign says when Sean Hannity asked Palin last night whether there should be an investigation of campaign contributions by Fannie and Freddie executives, she deferred saying, “that’s significant, but even more significant is the role that lobbyists play in this.”

Obama campaign staffers note that several of McCain’s top advisors – including campaign manager Rick Davis, vice presidential vetter Arthur Culvahouse, and McCain consigliere Charlie Black – lobbied on behalf of the mortgage giants.

ABC News’ Martha Raddatz, Lisa Chinn, Teddy Davis, Alyssa Litoff, Bret Hovell and Imtiyaz Delawala contributed to this report.